Knowledge of oncogenic mutations can inspire therapeutic strategies that are synthetically lethal, affecting cancer cells while sparing normal cells. Lenalidomide is an active agent in the activated B cell-like (ABC) subtype of diffuse large B cell lymphoma (DLBCL), but its mechanism of action is unknown. Lenalidomide kills ABC DLBCL cells by augmenting interferon β (IFNβ) production, owing to the oncogenic MYD88 mutations in these lymphomas. In a cereblon-dependent fashion, lenalidomide downregulates IRF4 and SPIB, transcription factors that together prevent IFNβ production by repressing IRF7 and amplify prosurvival NF-κB signaling by transactivating CARD11. Blockade of B cell receptor signaling using the BTK inhibitor ibrutinib also downregulates IRF4 and consequently synergizes with lenalidomide in killing ABC DLBCLs, suggesting attractive therapeutic strategies.
Highlights
► Lenalidomide kills ABC DLBCLs by decreasing expression of IRF4 and SPIB ► IRF4 and SPIB maintain ABC DLBCL viability ► IRF4 and SPIB block toxic IFNβ production while enhancing prosurvival NF-κB activity ► Lenalidomide and BCR pathway drugs synergize to inhibit IRF4 and kill ABC DLBCLs
Present address: Boğaziçi University, Department of Molecular Biology and Genetics, Laboratory of Genome Regulation, Kuzey Park Binasi, 3.Kat, Bebek 34342, Istanbul, Turkey